In manufacturing processes of metal oxide and metal hydroxide which are used as battery materials and the like, a common way to finally produce them as metal fine powder is to filter slurry containing the metal fine powder and thereafter dry the slurry by a flash dryer or a spray dryer to thereby obtain a dried product of the intended metal oxide or metal hydroxide.
More specifically, in the case where the flash dryer is used for the drying, aggregated wet powder obtained from the filtering process is conveyed in a tube of a dryer by hot air and during the conveyance process, is dried by convection heat transfer by the hot air, whereby the dried product of the metal fine powder is obtained.
In the case where the spray dryer is used for the drying, the slurry is sprayed and dispersed into a drying chamber through a disperser such as a rotary atomizer or a nozzle. Hot air is blown into the drying chamber, and sprayed droplets are dried while settling down in the hot air due to gravity, whereby the dried product of the metal fine powder is obtained.
The following documents can be cited as inventions to obtain metal oxide, metal hydroxide, and so on by using such a flash dryer, spray dryer, or the like.